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Author Topic:   question for KP lugnut
posted July 29, 2004 10:25 PM
KP,could you please tell me how to tell the difference in a 350 cfm holley and the 500?really appreciate it.

posted July 30, 2004 07:03 AM
350cfm (7448 model) has 1.5" butterflies. The 4412 (500cfm) has 1.687" or 1 11/16" butterflies.
The 7448 has straight leg boosters and the 4412 has downleg (aka "dropped" or "dogleg") boosters.
The 7448 venturi diameter will be 1 3/16" and the 4412 will be 1 3/8" (give or take a few thousandths due to Holley's "fine" assembly line quality LOL).
The choke horns usually will be stamped with the List # of the carb (7448, or 4412), unless it's either a custom built carb or many of the Dorton series carbs don't have any #'s because the bodies are "intercepted" off the assembly line before final machining and stamping.
Off the shelf, the 4412 will come with a 50cc accelerator pump and the 7448 will have only the smaller 30cc pump setup.
The two carbs also have VERY different metering blocks as well, but the above should give you enough to tell 'em apart.

Hope that helps,

posted July 30, 2004 10:58 PM
Thanks alot.I knew I could count on you to know.Came across a carb in a trade and it has the air horn milled off,wasnt sure what I had. Thanks again

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